A Symposium entitled "Precision and Molecular Structure" will be held at the University of Washington June 1-June 4, 1986. Participants will include scientists at the forefront of research in x-ray crystallography who will address such state-of-the-art topics as the use of anomalous scattering in phase determination, precision in virus structures, enzyme specificity, and protein modification. The symposium is in honor of Professor Lyle Jensen who will retire after nearly 40 years at the University, and who has had a profound influence on the course of crystallography. We are requesting support for travel and lodging for symposium participants.